US11036025B2 - Medical observation apparatus and medical observation system - Google Patents

Abstract

A medical observation apparatus includes: an optical structure including at least one lens; an image sensor configured to capture an image formed by the optical structure; a temperature sensor configured to detect an environmental temperature of the optical structure; and circuitry configured to generate temperature information based on a detection result of the temperature sensor, and calculate a second focal length obtained by correcting a first focal length based on the temperature information and the first focal length calculated based on a lens position.

Description

This application claims priority from Japanese Application No. 2019-057312, filed on Mar. 25, 2019, the contents of which are incorporated by reference herein in its entirety.

BACKGROUND

The present disclosure relates to a medical observation apparatus and a medical observation system.

In the related art, as a medical observation system for observing a minute part of a brain, heart, or the like of a patient who is an object to be observed when performing an operation on the minute part, an optical microscope system including a plurality of arm units, a support unit which implements movement with a total of 6 degrees of freedom, that is, 3 degrees of freedom of translation and 3 degrees of freedom of rotation, and a microscope unit which is provided at a distal end of the support unit and includes a magnifying optical system or an image sensor which magnifies the minute part has been known.

In recent years, when performing an operation using a microscope system, a navigation apparatus which detects an observation position of a microscope unit and a position of a treatment tool, and displays the observation position and the like on a preoperative image has been employed as auxiliary means for performing a more accurate operation (see, for example, JP 2000-75213 A). In a case of the navigation apparatus, for example, three or more light emitting diodes are attached to the microscope unit, positions thereof are measured by a charge-coupled device (CCD) camera, and an observation position is calculated in consideration of a focal length of an optical system of the microscope unit.

Further, in some microscope systems, information on image capturing of a focal length and the like at a current position of the microscope unit may be displayed.

SUMMARY

In the optical system included in the microscope unit, characteristics of a lens may change due to a change in environmental temperature during use and the like, and a focal length may change even at the same lens position. If the focal length changes, a focal length based on a lens position does not match an actual focal length, such that accurate information may not be obtained.

According to one aspect of the present disclosure, there is provided a medical observation apparatus including: an optical structure including at least one lens; an image sensor configured to capture an image formed by the optical structure; a temperature sensor configured to detect an environmental temperature of the optical structure; and circuitry configured to generate temperature information based on a detection result of the temperature sensor, and calculate a second focal length obtained by correcting a first focal length based on the temperature information and the first focal length calculated based on a lens position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an appearance configuration of a medical observation system according to a first embodiment;

FIG. 2 is a block diagram illustrating a configuration of a control device of the medical observation system according to the first embodiment;

FIG. 3 is a partial cross-sectional view illustrating a configuration of a main part of an imaging unit in a microscope unit according to the first embodiment;

FIG. 4 is a flowchart illustrating focal length calculation processing performed by the control device of the medical observation system according to the first embodiment;

FIG. 5 is a diagram for describing a focal length change depending on a temperature;

FIG. 6 is a diagram for describing an example of a correction result for each temperature;

FIG. 7 is a diagram for describing an example of a table for calculating a correction value used at the time of performing focal length calculation processing according to a modified example of the first embodiment;

FIG. 8 is a partial cross-sectional view illustrating a configuration of an optical unit of a microscope unit of a medical observation system according to a second embodiment; and

FIG. 9 is a partial cross-sectional view illustrating a configuration of an optical unit of a microscope unit of a medical observation system according to a third embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments for carrying out the present disclosure (hereinafter, referred to as embodiments) will be described with reference to the accompanying drawings. Note that the drawings are merely schematic, and portions for which the relationships between dimensions and the proportions are different among drawings may be included in the drawings.

First Embodiment

FIG. 1 is a diagram illustrating a configuration of a medical observation system according to a first embodiment. Amedical observation system1 illustrated inFIG. 1 includes amicroscope device2 having a function as a microscope that magnifies and captures an image of a minute structure of an object to be observed, a control device3 which comprehensively controls operation of themedical observation system1, a display device4 which displays the image captured by themicroscope device2, and aposition measurement device9 which measures a three-dimensional position of a microscope unit of themicroscope device2. Themicroscope device2 and the control device3 constitute a medical observation apparatus. Further, the display device4 and theposition measurement device9 constitute a navigation apparatus.

Themicroscope device2 includes abase unit5 that is movable on a floor surface, asupport unit6 supported by thebase unit5, and acolumnar microscope unit7 provided at a distal end of thesupport unit6 and magnifying and capturing an image of a minute part of the object to be observed. Further, themicroscope device2 is connected to a light source device8 which supplies illumination light to themicroscope device2 via alight guide81 implemented by an optical fiber or the like. The light source device8 emits illumination light under the control of the control device3.

In themicroscope device2, a cable group including, for example, a transmission cable including a signal line (coaxial cable) for signal transmission between the control device3 and themicroscope unit7, or a light guide cable for guiding illumination light from the light source device8 to themicroscope unit7 is arranged from thebase unit5 to themicroscope unit7. The cable group is arranged along thesupport unit6.

Thesupport unit6 includes a firstjoint unit11, afirst arm unit21, a secondjoint unit12, asecond arm unit22, a thirdjoint unit13, athird arm unit23, a fourthjoint unit14, afourth arm unit24, a fifthjoint unit15, afifth arm unit25, and a sixthjoint unit16. Thesupport unit6 includes four sets each including two arm units and a joint unit that rotatably connects one (distal end side) of the two arm units to the other one (proximal end side). Specifically, these four sets are (thefirst arm unit21, the secondjoint unit12, and the second arm unit22), (thesecond arm unit22, the thirdjoint unit13, and the third arm unit23), (thethird arm unit23, the fourthjoint unit14, and the fourth arm unit24), and (thefourth arm unit24, the fifthjoint unit15, and the fifth arm unit25).

The firstjoint unit11 has a distal end rotatably holding themicroscope unit7 and a proximal end held by thefirst arm unit21 in a state of being fixed to a distal end portion of thefirst arm unit21. Thefirst joint unit11 has a circular cylindrical shape and holds themicroscope unit7 so as to be rotatable around a first axis O₁which is a central axis in a height direction. Thefirst arm unit21 has a shape extending from a side surface of the firstjoint unit11 in a direction orthogonal to the first axis O₁.

The secondjoint unit12 has a distal end rotatably holding thefirst arm unit21 and a proximal end held by thesecond arm unit22 in a state of being fixed to a distal end portion of thesecond arm unit22. Thesecond joint unit12 has a circular cylindrical shape and holds thefirst arm unit21 so as to be rotatable around a second axis O₂which is a central axis in the height direction and is orthogonal to the first axis O₁. Thesecond arm unit22 has a substantial “L”-letter shape and an end portion of a vertical line portion of the “L”-letter shape is connected to thesecond joint unit12.

Thethird joint unit13 has a distal end rotatably holding a horizontal line portion of the “L”-letter shape of thesecond arm unit22, and a proximal end held by thethird arm unit23 in a state of being fixed to a distal end portion of thethird arm unit23. Thethird joint unit13 has a circular cylindrical shape and holds thesecond arm unit22 so as to be rotatable around a third axis O₃which is a central axis in the height direction, is orthogonal to the second axis O₂, and is parallel to a direction in which thesecond arm unit22 extends. The distal end of thethird arm unit23 has a circular cylindrical shape and a hole that penetrates in a direction orthogonal to a height direction of the circular cylindrical distal end is formed at a proximal end of thethird arm unit23. Thethird joint unit13 is rotatably held by thefourth joint unit14 through this hole.

Thefourth joint unit14 has a distal end rotatably holding thethird arm unit23 and a proximal end held by thefourth arm unit24 in a state of being fixed to thefourth arm unit24. Thefourth joint unit14 has a circular cylindrical shape and holds thethird arm unit23 so as to be rotatable around a fourth axis O₄which is a central axis in the height direction and is orthogonal to the third axis O₃.

Thefifth joint unit15 has a distal end rotatably holding thefourth arm unit24 and a proximal end fixedly attached to thefifth arm unit25. Thefifth joint unit15 has a circular cylindrical shape and holds thefourth arm unit24 so as to be rotatable around a fifth axis O₅which is a central axis in the height direction and is parallel to the fourth axis O₄. Thefifth arm unit25 includes a portion with an “L”-letter shape and a rod-shaped portion extending downward from a horizontal line portion of the “L”-letter shape. The proximal end of thefifth joint unit15 is attached to an end portion of a vertical line portion of the “L”-letter shape of thefifth arm unit25.

Thesixth joint unit16 has a distal end rotatably holding thefifth arm unit25 and a proximal end fixedly attached to an upper surface of thebase unit5. Thesixth joint unit16 has a circular cylindrical shape and holds thefifth arm unit25 so as to be rotatable around a sixth axis O₆which is a central axis in the height direction and is orthogonal to the fifth axis O₅. A proximal end portion of the rod-shaped portion of thefifth arm unit25 is attached to the distal end of thesixth joint unit16.

Thesupport unit6 having the above-described configuration implements movement with a total of 6 degrees of freedom, that is, 3 degrees of freedom of translation and 3 degrees of freedom of rotation, for themicroscope unit7.

The firstjoint unit11 to thesixth joint unit16 have electromagnetic brakes that prohibit rotation of themicroscope unit7 and thefirst arm unit21 to thefifth arm unit25, respectively. Each electromagnetic brake is released in a state in which an arm operation switch (described later) provided in themicroscope unit7 is pressed, and allows rotation of themicroscope unit7 and thefirst arm unit21 to thefifth arm unit25. Note that an air brake may be applied instead of the electromagnetic brake.

In addition to the electromagnetic brake described above, an encoder and an actuator may be mounted on each joint unit. For example, in a case where the encoder is provided in thefirst joint unit11, the encoder detects a rotation angle on the first axis O₁. The actuator is implemented by an electric motor such as a servo motor, and is driven according to a control of the control device3 to cause rotation at the joint unit by a predetermined angle. The rotation angle at the joint unit is set by the control device3 based on a rotation angle on each rotation axis (the first axis O₁to the sixth axis O₆), for example, as a value necessary for moving themicroscope unit7. As such, the joint unit provided with an active driving mechanism such as an actuator constitutes a rotation shaft that rotates actively according to a control of the driving of the actuator.

In themicroscope unit7, an imaging unit that magnifies and captures an image of the object to be observed, the arm operation switch that receives an operation input for releasing the electromagnetic brakes of thefirst joint unit11 to thesixth joint unit16 to allow the rotation of each joint unit, and a cross lever that may change a magnification and a focal length to the object to be observed in the imaging unit are provided in a casing having a circular cylindrical shape. While the user presses the arm operation switch, the electromagnetic brakes of the firstjoint unit11 to the sixthjoint unit16 are released. The configuration of the imaging unit will be described later.

The control device3 receives an imaging signal output from themicroscope device2, and generates display image data by performing predetermined signal processing on the imaging signal. Note that the control device3 may be installed inside thebase unit5 and integrated with themicroscope device2.

FIG. 2 is a block diagram illustrating a configuration of the control device of the medical observation system according to the first embodiment. The control device3 includes an image processor31, a temperature information generation unit32, a focal length calculation unit33, an input unit34, an output unit35, a storage unit36, and acontrol unit37. Note that, for example, a power supply unit (not illustrated) which generates a power supply voltage for driving themicroscope device2 and the control device3, supplies the power supply voltage to each component of the control device3, and supplies the power supply voltage to themicroscope device2 via the transmission cable may be provided in the control device3.

The image processor31 performs signal processing such as noise removal and A/D conversion as necessary on the imaging signal output from themicroscope unit7. The image processor31 generates a display image signal to be displayed on the display device4 based on the imaging signal after the signal processing. The image processor31 performs predetermined signal processing on the imaging signal to generate a display image signal including a subject image. Here, the image processor31 performs various known image processing such as detection processing, interpolation processing, color correction processing, color enhancement processing, and contour enhancement processing. The image processor31 outputs the generated image signal to the display device4.

Further, the image processor31 may include an auto-focus (AF) processor which outputs a predetermined AF evaluation value for each frame based on an input imaging signal of a frame, and an AF calculation unit which performs AF calculation processing such as selection of a frame or a focus lens position that is most suitable as a focusing position based on the AF evaluation value for each frame output from the AF processor.

The temperature information generation unit32 obtains a detection signal from atemperature sensor74 provided in themicroscope unit7 and generates temperature information. The temperature information generation unit32 extracts a detection value from an analog/digital detection signal obtained from the temperature sensor, and generates temperature information based on the detection value. The temperature information is output as an environmental temperature around the lens in alens unit71.

The focal length calculation unit33 calculates an actual focal length based on the temperature information generated by the temperature information generation unit32 and information on a lens position in thelens unit71 that is obtained from an actuator unit73 of themicroscope unit7. A method for calculating the focal length will be described later.

The input unit34 is implemented by a user interface such as a keyboard, a mouse, or a touch panel, and receives an input of various information.

The output unit35 is implemented by a speaker, a printer, a display, or the like, and outputs various information.

The storage unit36 is implemented by a semiconductor memory such as a flash memory or a dynamic random access memory (DRAM), and communication information data (for example, communication format information), a voice recognition table in which a frequency of voice and feature data are associated with each other, a processing table in which a voice recognition result and a processing content are associated with each other, and the like are recorded in the storage unit36. Note that various programs executed by thecontrol unit37 may be recorded in the storage unit36.

Thecontrol unit37 performs a driving control of each component including the control device3 and themicroscope unit7, an input and output control of information with respect to each component, and the like. Thecontrol unit37 generates a control signal by referring to the communication information data (for example, communication format information) recorded in the storage unit36, and transmits the generated control signal to themicroscope device2.

Note that thecontrol unit37 generates a synchronization signal and a clock for themicroscope unit7 and the control device3. A synchronization signal (for example, a synchronization signal for instructing an image capturing timing) or a clock (for example, a clock for serial communication) for themicroscope unit7 is transmitted to themicroscope unit7 through a line (not illustrated), and themicroscope unit7 is driven based on the synchronization signal and clock.

The image processor31, the temperature information generation unit32, the focal length calculation unit33, and thecontrol unit37 described above are each implemented by a general-purpose processor such as a central processing unit (CPU) including an internal memory (not illustrated) in which a program is recorded, or a dedicated processor such as various types of arithmetic circuits that performs a specific function, such as an application specific integrated circuit (ASIC).

Alternatively, the image processor31, the temperature information generation unit32, the focal length calculation unit33, and thecontrol unit37 described above may each implemented by a field programmable gate array (FPGA, not illustrated) which is a kind of programmable integrated circuit. Note that, in a case of the FPGA, a memory storing configuration data may be provided, and the FPGA, which is a programmable integrated circuit, may be configured based on the configuration data read from the memory.

Next, a configuration of the imaging unit of themicroscope unit7 will be described. As illustrated inFIG. 2, themicroscope unit7 includes thelens unit71, animage sensor72, the actuator unit73, atemperature sensor74, and alight emitting unit75.

Thelens unit71 is constituted by a plurality of lenses, and forms a subject image that has passed through thelens unit71 on an imaging surface of theimage sensor72. At least some of the plurality of lenses are movable along an optical axis.

FIG. 3 is a partial cross-sectional view illustrating a configuration of a main part of the imaging unit in the microscope unit according to the first embodiment. In thelens unit71, afirst lens711 to afifth lens715 are provided along an optical axis N_L. Thefirst lens711 to thefifth lens715 constitute an optical system in the imaging unit. According to the first embodiment, thefirst lens711 functions as an objective lens. Further, thefifth lens715 functions as a tube lens that forms an image on the imaging surface of theimage sensor72. Thefirst lens711 to thefifth lens715 are held by afirst holding unit721 to afifth holding unit725, respectively. Further, thefirst holding unit721 to thefifth holding unit725 are held inside acylindrical casing710. Among these, thethird holding unit723 and thefourth holding unit724 are movable in a direction of the optical axis N_Lby the actuator unit73.

Further, thecasing710 holds theimage sensor72 so that theimage sensor72 matches an image forming position of thefifth lens715.

Theimage sensor72 captures an image of a subject under the control of the control device3. Theimage sensor72 receives the subject image formed by thelens unit71 and converts the subject image into an electrical signal (imaging signal). Theimage sensor72 is implemented by a CCD image sensor or a complementary metal oxide semiconductor (CMOS) image sensor. In a case where theimage sensor72 is a CCD image sensor, for example, a signal processor (not illustrated) which performs signal processing (A/D conversion or the like) on the electrical signal (analog signal) obtained from the image sensor and outputs an imaging signal is packaged in a sensor chip or the like. In a case where theimage sensor72 is a CMOS image sensor, for example, a signal processor (not illustrated) which performs signal processing (A/D conversion or the like) on an electrical signal (analog signal) obtained by conversion from light to an electrical signal and outputs an imaging signal is included in the image sensor. Themicroscope unit7 outputs the generated imaging signal to the image processor31.

The actuator unit73 performs optical zoom processing for changing an angle of view or focus processing for changing a focal position by moving one or a plurality of lenses based on a control signal from the control device3. According to the first embodiment, at least one of thethird holding unit723 that holds thethird lens713 and thefourth holding unit724 that holds thefourth lens714 is moved in the direction of the optical axis N_L. The actuator unit73 is constituted by an actuator or an encoder that moves the lens.

Further, the actuator unit73 outputs lens position information to the control device3.

Thetemperature sensor74 is constituted by a known temperature detector such as a thermistor. Thetemperature sensor74 digitizes, for example, an electromotive force or a resistance that changes with temperature. Thetemperature sensor74 outputs a digitized detection result to the temperature information generation unit32.

Thetemperature sensor74 is provided on an outer surface of thecasing710. According to the first embodiment, thetemperature sensor74 is provided in a movement range of thethird lens713 in the direction of the optical axis N_Land on an outer circumferential surface of thecasing710. Note that thetemperature sensor74 may be provided on an inner wall of thecasing710 as long as thetemperature sensor74 does not affect the movement of the lens.

Thelight emitting unit75 is fixed at a predetermined position on a side surface of themicroscope unit7 and is constituted by three light emitting diodes (LEDs) that emit infrared light, respectively. The infrared light emitted from thelight emitting unit75 is used when theposition measurement device9 measures a three-dimensional position of themicroscope device2.

The display device4 receives, from the control device3, a three-dimensional image data generated by the control device3, and displays a three-dimensional image corresponding to the three-dimensional image data. Such a display device4 includes a display panel formed of liquid crystal or organic electro luminescence (EL).

Note that an output device which outputs information using a speaker, a printer, or the like may be provided in addition to the display device4.

Theposition measurement device9 is a device that measures a three-dimensional position of themicroscope unit7. Theposition measurement device9 includes an imaging unit91, a measurement unit92, a storage unit93, and a control unit94.

The imaging unit91 is constituted by an image sensor such as a CCD image sensor or a CMOS image sensor, and detects infrared rays radiated by thelight emitting unit75 of themicroscope unit7.

The measurement unit92 measures the three-dimensional position of themicroscope unit7 of themicroscope device2 using the infrared rays acquired by the imaging unit91.

The storage unit93 stores various programs executed by theposition measurement device9, and temporarily stores data that are being calculated by theposition measurement device9. The storage unit93 is constituted by a read only memory (ROM), a random access memory (RAM), or the like.

The control unit94 controls an operation of theposition measurement device9. The control unit94 is constituted by one or a plurality of processors such as a CPU, an FPGA, and an ASIC together with the measurement unit92.

Next, an overview of an operation performed using themedical observation system1 having the above-described configuration will be described. When an operator who is a user performs an operation on the head of a patient who is an object to be observed, the operator grips themicroscope unit7, moves themicroscope unit7 to a desired position in a state of keeping the arm operation switch of themicroscope unit7 pressed, determines an imaging visual field of themicroscope unit7, and then removes his/her finger from the arm operation switch, while visually observing an image displayed on the display device4. Thereby, the electromagnetic brakes are operated in the firstjoint unit11 to the sixthjoint unit16, and the imaging visual field of themicroscope unit7 is fixed.

Thereafter, the operator performs adjustment of the magnification and the focal length to the object to be observed, and the like.

Next, focal length calculation processing performed by the control device3 will be described with reference toFIG. 4.FIG. 4 is a flowchart illustrating focal length calculation processing performed by the control device of the medical observation system according to the first embodiment. When a focal length calculation instruction is input, thecontrol unit37 starts focal length calculation processing.

Thecontrol unit37 obtains lens position information (Step S101). Thecontrol unit37 obtains the lens position information on a lens position from the actuator unit73. The focal length calculation unit33 calculates a focal length (uncorrected focal length) based on the information on a lens position in thelens unit71 obtained from the actuator unit73 (Step S102). The uncorrected focal length corresponds to a first focal length.

Further, the temperature information generation unit32 obtains a detection signal from thetemperature sensor74 and generates temperature information (Step S103).

The focal length calculation unit33 calculates a correction value based on the temperature information generated in Step S103 (Step S104). The focal length calculation unit33 calculates the correction value by using the following Equation (1).
Correction value=(X−T)×Q  (1)

Here, Q=B(Y).

X: Obtained temperature (° C.) of thelens unit71

T: Reference temperature (° C.)

Q: Focal length change amount per unit temperature

B( ): Change amount conversion formula

Y: Uncorrected focal length

FIG. 5 is a diagram for describing a focal length change depending on a temperature. (a) ofFIG. 5 is a diagram illustrating a focal length when the temperature (environmental temperature) of thelens unit71 is 10° C. (b) ofFIG. 5 is a diagram illustrating a focal length when the temperature (environmental temperature) of thelens unit71 is 25° C. (c) ofFIG. 5 is a diagram illustrating a focal length when the temperature (environmental temperature) of thelens unit71 is 40° C. InFIG. 5, only thethird lens713 to be driven is illustrated, and the other lenses are not illustrated.

Further, in the first embodiment, the reference temperature is 25° C.

Even when all the lenses including thethird lens713 are arranged at the same positions, the focal position changes due to a change in lens characteristics depending on a temperature. InFIG. 5, a focal position P₂when the environmental temperature is 10° C. and a focal position P₃when the environmental temperature is 40° C. are different from a focal position P₁when the environmental temperature is 25° C. As such, even in a case where the lens position is not changed, the focal position changes depending on the environmental temperature. Therefore, the actual focal length also changes depending on the environmental temperature. Specifically, the focal length when the environmental temperature is 10° C. is smaller and the focal length when the environmental temperature is 40° C. is larger than the focal length when the environmental temperature is the reference temperature (25° C.)

The focal length calculation unit33 calculates the above-described amount of the focal length change depending on a temperature as a correction value for the focal position calculated based on the lens position, and corrects the focal position (Step S105).

FIG. 6 is a diagram for describing an example of a correction result for each temperature. For example, in a case where the focal length when the environmental temperature is 25° C. (reference temperature) is 500 mm (WD500), if a correction value when the environmental temperature is 10° C. is calculated to be −10 mm and a correction value when the environmental temperature is 40° C. is calculated to be +10 mm (a correction value when the environmental temperature is 25° C. is 0, because 25° C. is the reference temperature) according to Equation (1), an actual focal length (corrected focal length) when the environmental temperature is 10° C. is 490 mm (WD490), and an actual focal length (corrected focal length) when the environmental temperature is 40° C. is 510 mm (WD510). On the other hand, in a case of not performing the correction, the focal length (corrected focal length) is 500 mm (WD500) regardless of the environmental temperature. The corrected focal length corresponds to a second focal length.

Here, WD indicates a working distance.

Once the corrected focal length is calculated by the focal length calculation unit33, thecontrol unit37 outputs information on the calculated corrected focal length to the display device4 or the navigation apparatus (Step S106). As a result, a value closer to the actual focal length is output.

For example, the control unit94 of theposition measurement device9 calculates a focal position in an image based on the position of themicroscope unit7 measured by theposition measurement device9 and a direction of the optical axis of themicroscope unit7 at the position of themicroscope unit7, and generates a display image by applying information on a result of the calculation and the like to an image captured by themicroscope unit7. The focal position in the image captured by themicroscope unit7 is displayed on the display device4 together with the corrected focal length. The focal position in the image is indicated by, for example, an arrow.

In addition, a display image in which information on the corrected focal length is superimposed on the image captured by themicroscope unit7 may be displayed on the display device4.

According to the first embodiment described above, since the focal length is corrected based on the uncorrected focal length obtained based on the lens position and the detected environmental temperature in thelens unit71, the focal length calculation unit33 may obtain a focal length corresponding to a use environmental temperature.

Further, according to the first embodiment, since thetemperature sensor74 is arranged in the vicinity of the lens (here, the third lens713) to be driven, the temperature of the lens that causes the change in the focal length is used for the correction of the focal length, such that the focal length may be accurately corrected.

In the first embodiment described above, an example in which the focal length calculation unit33 calculates the correction value based on the uncorrected focal length and the temperature information has been described, but the correction value may also be calculated based on optical characteristic values such as a thermal expansion coefficient, a refractive index, and a temperature characteristic value of the lens, in addition to the uncorrected focal length and the temperature information. For these optical characteristic values, for example, values measured at the reference temperature (here, 25° C.) are used as calibration values (values at the reference temperature) at the time of product shipment in a factory.

Modified Example of First Embodiment

Next, a modified example of the first embodiment will be described with reference toFIG. 7.FIG. 7 is a diagram for describing an example of a table for calculating a correction value used at the time of performing focal length calculation processing according to a modified example of the first embodiment. Since a medical observation system according to the modified example has the same configuration as that of themedical observation system1 according to the first embodiment described above, a description thereof is omitted. In the first embodiment described above, an example in which the correction value is calculated by using an equation (Equation (1)) has been described. However, in the modified example, the correction value is obtained by using a preset correction value output table. Each value in the correction value output table is set in consideration of optical characteristic values such as a thermal expansion coefficient, a refractive index, and a temperature characteristic value of the lens, in addition to the uncorrected focal length and the temperature information.

In the modified example, a flow of focal length calculation processing is the same as that in the flowchart illustrated inFIG. 4. Here, in Step S104, the focal length calculation unit33 acquires the correction value by using the correction value output table illustrated inFIG. 7 instead of calculating the correction value by using Equation (1). The focal length calculation unit33 outputs a correction value for each temperature separately for a case where the uncorrected focal length is 200 mm (WD200) or more and less than 400 mm (WD400), and a case where the uncorrected focal length is 400 mm (WD400) or more and 600 mm (WD600) or less, with reference to the correction value output table.

The subsequent processing is the same as that inFIG. 4.

In the modified example described above, similarly to the first embodiment described above, since the focal length is corrected based on the uncorrected focal length obtained based on the lens position and the detected environmental temperature in thelens unit71, the focal length calculation unit33 may obtain an accurate focal length corresponding to a use environmental temperature.

Second Embodiment

Next, a second embodiment will be described with reference toFIG. 8.FIG. 8 is a partial cross-sectional view illustrating a configuration of an optical unit of a microscope unit of a medical observation system according to the second embodiment. The medical observation system according to the second embodiment has the same configuration as that of themedical observation system1 of the first embodiment described above except that an arrangement position of thetemperature sensor74 is changed, and thus a description of a configuration of each component is omitted. Hereinafter, a difference from the first embodiment will be described.

Thetemperature sensor74 is provided on a surface of theimage sensor72 that is opposite to a surface facing thecasing710. Similar to the first embodiment, thetemperature sensor74 outputs a digitized detection result to the temperature information generation unit32.

In the second embodiment, a flow of focal length calculation processing is the same as that in the flowchart illustrated inFIG. 4. For calculation of the correction value, Equation (1) or the correction value output table (seeFIG. 7) may be used.

In the second embodiment described above, similarly to the first embodiment described above, since the focal length is corrected based on the uncorrected focal length obtained based on the lens position and the detected environmental temperature in thelens unit71, the focal length calculation unit33 may obtain an accurate focal length corresponding to a use environmental temperature. Further, according to the second embodiment, since thetemperature sensor74 is arranged in the vicinity of theimage sensor72, a temperature of a member that causes the change in the lens temperature is used for the correction of the focal length, such that the focal length may be accurately corrected.

Third Embodiment

Next, a third embodiment will be described with reference toFIG. 9.FIG. 9 is a partial cross-sectional view illustrating a configuration of an optical unit of a microscope unit of a medical observation system according to the third embodiment. The medical observation system according to the third embodiment has the same configuration as that of themedical observation system1 of the first embodiment described above except that an arrangement position of thetemperature sensor74 is changed, and thus a description of a configuration of each component is omitted. Hereinafter, a difference from the first embodiment will be described.

Thetemperature sensor74 is provided on any one of the plurality of lenses. According to the third embodiment, thetemperature sensor74 is provided on a lens having a refractive index highly dependent on temperature, specifically, a lens (here, the fourth lens714) having the highest thermal expansion coefficient. Note that thetemperature sensor74 is provided outside a light passing region of the lens.

Similar to the first embodiment, thetemperature sensor74 outputs a digitized detection result to the temperature information generation unit32.

In the third embodiment, a flow of focal length calculation processing is the same as that in the flowchart illustrated inFIG. 4. For calculation of the correction value, Equation (1) or the correction value output table (seeFIG. 7) may be used.

In the third embodiment described above, similarly to the first embodiment described above, since the focal length is corrected based on the uncorrected focal length obtained based on the lens position and the detected environmental temperature in thelens unit71, the focal length calculation unit33 may obtain an accurate focal length corresponding to a use environmental temperature.

Further, according to the third embodiment, since thetemperature sensor74 is arranged directly on a lens having a refractive index highly dependent on temperature, the temperature of the lens that directly affects an error of the focal length is used for the correction of the focal length, such that the focal length may be accurately corrected.

Hereinabove, the embodiments for carrying out the present disclosure have been described, but the present disclosure should not be limited only to the embodiments described above. For example, it is sufficient that thesupport unit6 includes at least one set including two arm units and a joint unit that rotatably connects one of the two arm units to the other one.

Note that although the configuration in which the focal length may be changed by moving the lens has been described in the first to third embodiments as an example, a configuration in which the optical system has a fixed focal length and the focal length is corrected based on a detection result obtained by the temperature sensor may also be possible.

Further, although the configuration in which one temperature sensor is provided has been described in the first to third embodiments as an example, a configuration in which a plurality of temperature sensors are provided and an average value, a mode value, or the like is used as temperature information to obtain a correction value may also be possible.

Moreover, the microscope device may be arranged so as to be suspended from a ceiling of a place where the microscope device is installed.

As described above, the present disclosure may include various embodiments and the like without departing from the technical idea described in the claims.

As described above, the medical observation apparatus and the medical observation system according to the present disclosure are useful for obtaining a focal length corresponding to a use environmental temperature.

According to the present disclosure, it is possible to obtain a focal length corresponding to a use environmental temperature.

Although the disclosure has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.

Claims (8)

What is claimed is:

1. A medical observation apparatus comprising:

an optical structure including at least one lens;

an image sensor configured to capture an image formed by the optical structure;

a temperature sensor configured to detect an environmental temperature of the optical structure;

a memory that stores data including first focal length correction values according to temperature and second focal length correction values according to temperature, the first focal length correction values being for a first lens within a first range of uncorrected focal length, and the second focal length correction values being for a second lens within a second range of uncorrected focal length; and

circuitry configured to

generate temperature information based on a detection result of the temperature sensor,

calculate a focal length of the at least one lens based on a lens position of the at least one lens,

identify whether the at least one lens belong to the first lens or the second lens based on the calculated focal length of the at least one lens, and

calculate a second focal length obtained by correcting the calculated focal length of the at least one lens based on the data, by identifying a correction value corresponding to the temperature information from either the first focal length correction values or the second focal length correction values depending on whether the at least one lens has been identified as belonging to the first lens or the second lens.

2. The medical observation apparatus according toclaim 1, further comprising an actuator configured to drive the at least one lens of the optical structure,

wherein the circuitry is configured to calculate the first focal length based on lens position information obtained from the actuator.

3. The medical observation apparatus according toclaim 1, wherein the circuitry is configured to correct the first focal length by using the temperature information, the first focal length, and optical characteristic values of the optical structure.

4. The medical observation apparatus according toclaim 1, further comprising a casing configured to hold the optical structure,

wherein the temperature sensor is provided on the casing.

5. The medical observation apparatus according toclaim 1, wherein the temperature sensor is provided on the image sensor.

6. The medical observation apparatus according toclaim 1, wherein the temperature sensor is provided on the lens included in the optical structure.

7. The medical observation apparatus according toclaim 1, wherein information on the calculated second focal length is output to an external navigation apparatus.

8. A medical observation system comprising:

a medical observation apparatus including

an optical structure including at least one lens,

an image sensor configured to capture an image formed by the optical structure,

a temperature sensor configured to detect an environmental temperature of the optical structure,

a memory that stores data including first focal length correction values according to temperature and second focal length correction values according to temperature, the first focal length correction values being for a first lens within a first range of uncorrected focal length, and the second focal length correction values being for a second lens within a second range of uncorrected focal length, and

circuitry configured to

generate temperature information based on a detection result of the temperature sensor,

calculate a focal length of the at least one lens based on a lens position of the at least one lens,

identify whether the at least one lens belong to the first lens or the second lens based on the calculated focal length of the at least one lens, and

calculate a second focal length obtained by correcting the calculated focal length of the at least one lens based on the data, by identifying a correction value corresponding to the temperature information from either the first focal length correction values or the second focal length correction values depending on whether the at least one lens has been identified as belonging to the first lens or the second lens;

a position measurement device configured to measure a three-dimensional position of a casing on which the image sensor is provided; and

a display panel configured to display information on the three-dimensional position of the casing measured by the position measurement device, together with the image captured by the image sensor.

Images